类数组
<script type="text/javascript">
	var obj = {
		"1" : "a",
		"2" : "b",
		"3" : "c",
		"length" : 3,
		"push" : Array.prototype.push,
		"splice" : Array.prototype.splice
	}
	obj.push('b');
	console.log(obj);
	//属性要为索引(数字)属性，必须有length属性，最好加上push
	//好处

</script>

<script type="text/javascript">
	Array.prototype.push = function (target){
		this[this.length] = target;
		this.length ++;
	}
</script>

<script type="text/javascript">
	var obj = {
		"0" : "a",
		"1" : "b",
		"2" : "c",
		age : 12,
		sex : "male",
		"length" : 3,
		push : Array.prototype.push,
		splice : Array.prototype.splice
	}

	console.log(obj);
	console.log(obj.sex);
	for(var prop in obj){//遍历属性
		console.log(obj[prop])
	}
</script>